My 2cents if I may. You sound super keen on wanting this specific car, any reason for it?
As mentioned by the other guys, we've been in your shoes but you need to guide us on why you want it. The look, is it in stock form or modded, something normally pulls a young guys chain and we need to figure what that something is.
My first response would have been on par with
@AshG108 but being past that now, it's been 1 week since you posted this, is the car still available? If it is you need to start questioning why? Great finds sell within hours, not days and you buying a first BMW you want a great find. Also, is it with a dealership or private? If dealer, share a link, there's guys on here with eagle eyes that can point out valid problems by looking at pics.
Don't buy the car coz if something goes wrong cuzzy can just fix it, not everyone actually knows how to work on BMW's. My cuzzy also knows a thing or 2 about cars but I won't let him touch mine personally unless he;s helping me wash it, if he messes up you're just gonna get a sorry. Rather make sure there are good guys around in your area or ask on the forum for pointers on mechanics in your area, if there are maybe reach out to them to have a chat about their estimations in the past 6 months with 1series cars coming in for work.
My recommendation would be to take your time with this, you already know how much you're gonna pay monthly so put that aside now until you find a great buy. Then you'll have extra for a deposit or even to keep aside as an oh shit fund coz trust me, oh shit comes when you least expect it.
When it comes to buying cars or houses you should live by one rule regarding affordability and maintenance, take whatever it will cost you monthly and double the amount, if you can put away that amount for the next 6 months without touching it then go for it, you should be fine. If not, then you're not ready for it yet.